T7 bacteriophage DNA

Note Results [83H1] of total intensity light scattering on linear T7 bacteriophage DNA (M=26.43-10 g-mol , from sequence analysis), analyzed according to Sharp and Bloomfield [68S1],... 

Bacteriophage T7 Bacteriophage T7 and its close relative T3 are relatively small DNA viruses that infect Escherichia coli. (Some strains of Shigella and Pasteurella are also hosts for phage T7.) The virus particle has an icosahedral head and a very small tail. The virus particle is fairly complex, with S different proteins in the head and 3-6 different proteins in the tail. One tail protein, the tail fiber protein, is the means by which the virus particle attaches to the bacterial cell surface. Only female cells of Escherichia coli can be infected with T7 male cells can be infected but the multiplication process is terminated during the latent period. 

The role of OJ in strand breakage was shown with the DNA of the T7 bacteriophage, in this process OH radicals were implicated The possible relationship with spontaneous cancer has been stressed... 

Sheared and melted segments of bacteriophage T2 DNA (MW= 1.3X10 ) rena-tured 19.2% as fast as sheared and melted DNA from T7 bacteriophage under the same conditions of temperature, ionic strength, and concentration. What is the MW of T7 DNA ... 

Lawley PD, Lethbridge JH, Edwards PA, Shooter KV. Inactivation of bacteriophage T7 by mono- and difunctional sulphur mustards in relation to crosslinking and depurination of bacteriophage DNA. J Mol Biol. 1969 39 181 198. 

Schafer, R., Zillig, W. The effects of ionic strength on termination of transcription of DNAs from bacteriophages T4, T5 and T7 by DNA-dependent RNA polymerase from Escherichia coli and the nature of termination by factor q, Europ. J. Biochem. 33, 215-226 (1973b). 

Tabor, S., and Richardson, C.C. (1987) Selective oxidation of the exonuclease domain of bacteriophage T7 DNA polymerase./. Biol. Chem. 262, 15330-15333. 

Figure 12.8 Some other active-site coordination motifs in mononuclear zinc enzymes from left to right bacteriophage T7 lysozyme, 5-aminolaevulinate dehydratase, Ada DNA repair protein. (Reprinted with permission from Parkin, 2004. Copyright (2004) American Chemical Society.)...

Figure 5-13 Electron micrograph of a DNA molecule (from a bacterial virus bacteriophage T7) undergoing replication. The viral DNA is a long ( 14 pm) duplex rod containing about 40,000 base pairs. In this view of a replicating molecule an internal "eye" in which DNA has been duplicated is present. The DNA synthesis was initiated at a special site (origin) about 17% of the total length from one end of the duplex. The DNA was stained with uranyl acetate and viewed by dark field electron microscopy. Micrograph courtesy J. Wolfson and D. Dressier.

A sample of double-stranded DNA is denatured. One of the resulting single strands is used as a template to direct the synthesis of a complementary strand of radioactive DNA using a suitable DNA polymerase. The "Klenow fragment" of E. coli, DNA polymerase I, reverse transcriptase from a retrovirus, bacteriophage T7 DNA polymerase, Taq polymerase, and specially engineered enzymes produced from cloned genes have all been used. 

Some bacteriophage encode their own DNA polymerases. However, they usually rely on the host cell to provide accessory proteins. The sequence of the DNA polymerase from phage T7 is closely homologous to that of the Klenow fragment and the 3D structures are similar. The 80-kDa T7 polymerase requires the 12-kDa thioredoxin from the host cell as an additional subunit. It has been genetically engineered to improve its usefulness in DNA sequencing 278... 

The T-odd bacteriophages Tl, T3, T5, and T7 are medium-sized phage with linear duplex DNA genomes. Replication of linear DNA in these and in many other genomes presents a problem. Even if the RNA primer segment is made at the very 3 end of the template strand, there will be a gap in the final replicated strand when the primer is digested out. Since there is no known enzyme that will add to the 3 end of a chain, this gap will remain unfilled. The problem is solved by terminal redundancy, the presence of a common 260-nucleotide... 

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